Until the 18th century, both African rulers and European traders were happy to trade in slaves.
The slave trade began with Portuguese and Spanish traders taking African slaves to the American colonies which they had conquered in the 15th century. Around 350,000 Africans were taken in this way as slaves to the Americas.
In the 16th century English pirates started selling slaves to the Spanish colonies. Sir John Hawkins was the first sea captain to do so.
In 1713, the Treaty of Utrecht was signed. Spain gave British slave traders the contract, known as the Asiento, to trade 144,000 slaves a year to Spanish South America. After 1700, the number of slaves being transported increased greatly.
It has been estimated that overall, about 12 million Africans were captured to be taken to the Americas as slaves.
In 1770 approximately 100,000 slaves were shipped from Africa to the Americas. British ships carried about 50,000 of these.
British trading ships took part in the slave trade up until its eventual abolition in 1807.